In the related art, as a bearing used for a high-speed rotating body, a radial bearing is known which is used in a state of being attached to a rotary shaft so as to encircle the shaft. As such a radial bearing, a radial foil bearing is well known, including a thin sheet-shaped to foil which forms the bearing surface, a back foil which elastically supports the top foil, and a cylindrical bearing housing which accommodates the top foil and the back foil. As the back foil of the radial foil bearing, a bump foil is mainly used in which a thin sheet is formed in a wave sheet shape.
In some foil bearings, for example, in order to improve the damping effect using friction between foils or to increase the rigidity of the top foil, an intermediate foil is inserted between the top foil and the back foil (refer to Patent Document 1).
In such a radial foil bearing, in general, in order to prevent the detachment of the top foil or the bump foil from the bearing housing, one end portion (toe portion) thereof is directly fixed to the bearing housing or is indirectly fixed thereto via a spacer, using spot welding. Additionally, in general, the intermediate foil is disposed on the entire circumference of the bearing housing similarly to the top foil, and one end portion thereof is also fixed to the bearing housing through welding.
In addition, in Patent Document 2, without using welding, both ends (both ends in the circumferential direction) of a top foil are locked by being thrust against fixing walls of the inner wall of a housing, to be fixed thereto.